Pennisetum purpureum plant named ‘Prince’

ABSTRACT

Pennisetum purpureum  ‘Prince’ is a semi-dwarf, purple-foliaged napiergrass. It is a perennial in USDA hardiness zones 8-10, and a vigorous annual in more northern zones.

Botanical designation: Pennisetum purpureum (L.) Schum. ‘Prince’.

BACKGROUND OF THE INVENTION

The present invention relates to a new and distinct cultivar ofPennisetum purpureum, commonly called napiergrass, hereinafter referredto by its cultivar name ‘Prince’. This cultivar is grown primarily as anornamental for landscape use, and for use as a potted plant.

Seeds of two napiergrass accessions, designated Anae Roxo CNPGL, werereceived from CENARGEN/EMBRAPA in Brazil in April 1996. These were grownunder quarantine in the greenhouse during the winter of 1996-97. Theysegregated for a wide variety of green and various shades of purpleplants with a range of vigor. The most vigorous purple pigmented plantin each accession, given the Tifton numbers N240 and N241, were selfed.Seeds of these plants were planted in the field in 1997. The progeniesfrom these selfed plants again segregated for color and vigor in thefield. Three vigorous plants, from each accession, with different shadesof purple pigment development were vegetatively propagated for furtherevaluation in a napiergrass maintenance nursery in 1998. In 1999, twoaccessions, N241-5 (dwarf) and N241-8 (semidwarf) were selected forfurther evaluation.

In 1999, multi-plant observation plantings were made at Tifton (USDAZone 8a). Replicated tests were planted in 2000 at Blairsville (USDAZone 6b), Griffin (USDA Zone 7b), and Savannah (USDA Zone 8b). Plantingswere made at Tifton in 2001 and 2003. All test sites except Tifton wereirrigated. Plants in Blairsville and Griffin did not recover in 2001following temperatures as low as −17° C. Plants in Tifton and Savannahsurvived when exposed to low temperatures of −6° C. and −8° C.,respectively.

In 2003 the name ‘Prince’ was assigned to N241-8.

‘Prince’ has been asexually propagated at Tifton by stem cuttings since2002. Stem cuttings with two nodes tended to produce the most shoots,although somewhat reduced in vigor, based on three-week plant heights.The characteristics of the cultivar have been stable and reproduced trueto type in successive vegetative generations.

‘Prince’ has been compared to Pennisetum setaceum ‘Rubrum’ (unpatented)and to Pennisetum purpureum ‘Princess’ (U.S. Plant patent applicationSer. No. 11/151,587). The ‘Prince’ plant is almost twice as high as‘Rubrum’ and ‘Princess’. ‘Prince’ has a similar base circumference andsimilar number of tillers to ‘Princess’, but has almost twice the topcanopy spread (diameter of arching leaves at top of plant). The ‘Prince’plant has a much greater base circumference, top canopy spread, and morethan twice the number of tillers as ‘Rubrum’. ‘Prince’ has significantlylonger leaves that ‘Princess’ and ‘Rubrum’, with similar leaf width to‘Princess’, but much wider than ‘Rubrum’.

SUMMARY OF THE INVENTION

‘Prince’ has not been observed under all possible environmentalconditions, and the phenotype may vary somewhat with changes in light,temperature, soil, and rainfall without, however, any variance ingenotype.

The following traits have been observed and represent thecharacteristics of the new cultivar. In combination thesecharacteristics distinguish ‘Prince’ from other varieties in commerceknown to the inventors.

-   -   1) Greater plant height and top canopy spread than ‘Princess’        and greater height, plant circumference and tiller number than        ‘Rubrum’.    -   2) Longer leaf length than ‘Princess’ and greater leaf length        and width than ‘Rubrum’.    -   3) Greater vigor under irrigated conditions than ‘Rubrum’.    -   4) Greater cold hardiness (USDA Zone 8) than ‘Rubrum’.

BRIEF DESCRIPTION OF DRAWINGS

The accompanying illustration shows characteristics of the new cultivarin a photograph as true to color as is reasonable to make inillustrations of this nature.

FIG. 1. A two-year-old plant growing in full sun in the ground atSavannah, Ga. (Aug. 1, 2002). The plant is 218 cm high, with a basecircumference of 371 cm.

BOTANICAL DESCRIPTION OF THE PLANT

A detailed description of ‘Prince’ follows. Colors are based on TheRoyal Horticulture Color Chart, 2001 edition.Measurements/characteristics were taken from one, two, andthree-year-old plants grown in the ground under full sun at Tifton, Ga.(USDA Zone 8a ). Measurements are the average of 5 to 10 samples.

-   Classification:    -   -   Botanical—‘Prince’ is a cultivar of Pennisetum purpureum.        -   Parentage.—Seed from unkonwn napiergrass accessions.        -   Propagation.—Vegetatively by stem cuttings.-   Plant: The plant is perennial in USDA hardiness zones 8-10, and can    be grown as a vigorous annual in more northern zones.    -   -   Size.—The height of the plant ranged from 94 to 200 cm under            different environmental conditions, with an average height            of 159 cm. The base circumference ranged from 66 to 259 cm,            with an average of 157 cm, with 20 to 91 tillers,            averaging 52. The top canopy spread, or diameter of arching            leaves at the top of the plant ranged from 138 to 259 cm,            with an average of 186 cm.        -   Vigor.—The plant is quite vigorous, and produced 40 tillers            in one year under non-irrigated conditions, and twice that            number of tillers under irrigated conditions.

Two or three node cuttings with foliage removed root well in 8.3 cmliner pots, with rooting percentages in excess of 90%. Well rootedliners shifted from 8.3 cm pots to #5 (19.0 liter) containers inmid-April produced salable plants at a commercial nursery in 40 days.After cutting back, plants were again salable after 57 days. In 19 litercontainers using a pine bark-based substrate, paclobutrazol drencheswere not economically feasible for reducing plant growth. Hard pruningto control plant size results in good regrowth.

-   Leaf/stems: Initial leaves on ‘Prince’ emerge with a purple midrib    (187B on the adaxial side and 187A on the abaxial side) and a    mottled mixture of purple (187C) and green (137B) blade. Later, the    leaves emerge purple (187C) on both the adaxial and abaxial sides    from the whorls. The leaf blade is flat, narrow, pointed at the end,    sessile to the stem, and connected to the stem internode via the    leaf sheath. The inside of the leaf collar is lined with abundant 2    mm long trichomes. There is bloom (155C) on the stems, abundant    trichomes (1 to 2 mm long) on the sheath, trichomes (up to 4 mm    long) 12 cm up the margin of the blade from the collar, and sparse    trichomes (1 mm long) on the adaxial leaf surface. Margins of leaf    blades have prominent trichomes (0.2 mm long). The abaxial leaf    surface is smooth. Leaf color of both the adaxial and abaxial leaf    surfaces best fits the greyed-purple group 187B.

The length of leaf ranges from 84 to 86 cm under different environmentalconditions, with an average length of 84 cm. The leaf width ranges from29 to 35 mm, with an average width of 31 mm.

-   Flowering: These plants flower under short days, less than 11 hours    sunlight per day, and remain vegetative without producing    inflorescences in the area of development and proposed use. Plants    freeze due to cold temperatures before inflorescences are produced.

Plants are not recommended for landscape use in areas where a hardfreeze does not regularly occur by December 1 (USDA 9-11) sincereseeding may be an issue, particularly in humid, subtropicalenvironments.

-   Diseases: Helminthosporium leaf spot has been noted on the foliage    in the field and under overhead sprinklers in container nurseries,    but control has not been necessary. Two-lined spittlebug (Prosapia    bicinta (Say)) has also been noted to feed on the bases of field and    container-grown plants. In the field, plants should be cut back in    the late winter to remove debris that harbors spittlebugs.

1. A new and distinct variety of Pennisetum purpureum plant,substantially as herein described and illustrated.